Tracheal tube with bulged cuff

ABSTRACT

The invention concerns a tracheal tube with an inflatable cuff surrounding the tube which has a sealing function against the trachea, and which is through a separate channel connected to the surroundings to monitor and regulate the inside pressure in the inflated cuff. The particular feature of the inflatable cuff is a number of local bulges distributed along the circumference of the cuff. With the invention it is accomplished that the sealing in the areas with bulges becomes effective, because the channels formed by the length-wise folds in the cuff are interrupted by thin-walled bulges, in such a way that liquid and secretions do not penetrate down into the patient&#39;s lungs.

The present invention relates to a tracheal tube with an inflatableballoon, around the tube, the so called cuff which is in contact withthe tracheal wall with the purpose of sealing the airway, and which isthrough a separate channel connected to the outside in order to monitorand regulate the pressure within the cuff. Such tracheal tubes are usedfor controlled ventilation of the lungs during anaesthesia and intensivecare, during which he cuff seals up for respiratory air between theinside of the trachea and the tracheal tube. Apart from this, the cuffshall prevent liquid and secretions from entering the lungs.Additionally, it is important that the pressure of the cuff against thetracheal wall does not impede the blood supply to the tracheal mucosa.The best way to accomplish these functions is to use cuffs with adiameter larger than that of the trachea, because a homogeneous pressureon the tracheal wall is then achieved, as this pressure is regulated bythe inside pressure in the cuff only. However, a high-volume cuff hascertain drawbacks. The larger diameter of the cuff in relation to thatof the trachea implies that the cuff has longitudinal folds when it isinflated inside the trachea, and these folds will create channelsthrough which liquid and secretions with bacteria may get past the cuffand result in infection of the lungs.

From WO 95/09665 is known a tracheal tube comprising a cuff with anumber of axially arranged ring-formed bulges providing a number ofring-formed contacts between the cuff and the trachea. From DE-A-35 19626 (D2) is known a balloon catheter for the treatment of vessels, e.g.coronary vessels. The balloon is equipped with a distal portioncomprising circumferential rings to help inflating the balloon.

The purpose of this invention is to design a tracheal tube which has theadvantages of the known tracheal tubes, but prevents the disadvantage offorming channels between the trachea and the cuff. In accordance withthe invention, this problem is solved with a tracheal tube as defined inclaim 1.

More specifically, it is stated in claim 1 that the cuff has a number oflocal bulges distributed along the circumference of the balloon. In thisway it is ensured that the channels, which are formed by the length-wisefolds when the cuff is inflated inside the trachea, will be interruptedby areas with bulges. The thickness of the membrane in the bulges isreduced in comparison with the thickness of the membrane in the rest ofthe cuff. By this is ensured that the lengthwise folds which are formed,will be tightly closed by areas with bulges and that transport of liquidand secretions past the areas with local bulges is prevented.

By imparting to the bulges an elongate shape, as stated in claim 2, withthe longitudinal axis in the direction of the circumference, it isfurthermore ensured that the length-wise folds are interrupted bytransverse bulges.

In another version according to claim 3, the bulges have an elongateshape with the longitudinal axis in an angled direction in relation tothat of the circumference. As a result, the bulges become longer in thelongitudinal direction, and transport of liquid in a length-wise fold isreduced, because a length-wise fold will pass a longer distance withthin-walled bulges, if the orientation of the bulges is angled comparedto transversal.

By giving the balloon two or more rows of bulges, according to claim 4,the length-wise folds will be interrupted by one or more bulges, and thetransport of liquid will be reduced.

It will be advantageous, as stated in claim 5, if the bulges in each roware staggered in relation to each other, so that any fold in thelength-wise direction will be crossing a bulge.

In an advantageous version, according to claim 6, the bulges in twoadjacent rows are placed with different angled directions of thelongitudinal axis. By this, additional safety is obtained againstuninterrupted folds with channels from the area above the cuff to thearea below the cuff. As a result, any transport of liquid in alength-wise fold is reduced.

The channels that are formed when the bulges collapse against the insideof the tracheal wall must be very narrow in order to effectively preventtransport of fluid. Accordingly, the material of the bulges must be verysoft and very thin-walled, and it has been proved that a good result isobtained with a wall-thickness of less than 30 micrometer. Because theareas with bulges are pressed against the tracheal wall, the reducedwall-thickness in the bulges will not reduce the ability of the cuff toresist pressure during the inflation.

A detailed description of the invention is described in the followingtext with reference to the drawings, where

FIG. 1 shows an example of a conventional tracheal tube,

FIG. 1a shows the known catheter placed with the inflated cuff insidethe trachea,

FIG. 2 shows a sample of the catheter in accordance with the invention,

FIG. 2a shows the catheter shown in FIG. 2 placed inside the tracheawith the inflated cuff.

The known tracheal tube, which is shown in FIG. 1 with the cuff 4 ininflated state, consists of a tube 3 intended for intubation into thetrachea, as shown in FIG. 1a. Through this tube the lungs can beventilated, as the cuff blocks the passage of air between the tube 3 andthe inside of the trachea 2.

A thin tube 7 connects the inside of the cuff with the surroundings andthrough this tube the inside pressure of the cuff may be accuratelyregulated. The cuff is inflated with atmospheric air and, as seen inFIG. 1, the cuff spreads over a certain length of the tube 3 and ispermanently bonded to the tube at both its ends. At extubation, the cuffis emptied though the thin tube 7 and collapses around the tube 3, afterwhich the tube can be removed. The cuff 4 has a larger diameter than thetrachea itself 1 and when it is inflated inside the trachea, folds 5will be formed, as shown in FIG. 1a. There will be length-wise channelsin the folds 5, through which liquid and secretions may pass from thearea above the cuff to the area below the cuff. Due to this, the knowncuff involves a risk of infection of the patients lungs.

FIG. 2 shows a version of the tracheal tube in accordance with theinvention, where the cuff 4 a has a number of bulges 6 in the area whichis in contact with the tracheal wall. As demonstrated in FIG. 2a, thebulges 6 will collapse when the cuff is inflated after the tube has beenplaced inside the trachea and simultaneously the length-wise folds willbe interrupted by the area with bulges.

In the version shown in FIGS. 2 and 2a, the bulges are elongated withthe longitudinal axis in the direction of the circumference and at thesame time it has two rows of bulges which are staggered in thelength-wise direction of the cuff. This version is advantageous, becauseit effectively prevents length-wise folds from passing through the areawithout being interrupted by bulges, and in this way uninterruptedchannels from the area above the cuff to the area below the cuff isprevented. Meanwhile, the bulges may have any other shape or orientationand there may be more than two rows.

It is important that the wall of the cuff where the bulges are placed isflexible, so that the folds at this place do not form channels with across-section sufficient for passage of liquid or secretions containinginfectious material. To achieve this, it is appropriate for cuffsmanufactured from pvc that the wall-thickness in the areas with bulgesis less than 30 micrometer.

What is claimed is:
 1. A tracheal tube comprising a high-volumeinflatable cuff surrounding the tube, said cuff adapted to be introducedinto and seal against a trachea of a patient, the cuff being connectedto surroundings of the patient through a separate channel in order tomonitor and regulate pressure within the cuff in an inflated state, thecuff comprising an inflatable membrane formed with inflatable bulgesdistributed over that area of the cuff which when inflated is in contactwith the trachea, wherein the bulges are spaced apart around acircumference of the cuff so as to be surrounded by membrane that doesnot include bulges, the bulges being collapsible when brought intocontact with the trachea.
 2. A tracheal tube according to claim 1,wherein the bulges have an elongate shape with a longitudinal axisaligned in a direction of the circumference of the cuff.
 3. A trachealtube according to claim 1, wherein the bulges have an elongate shapewith a longitudinal axis of the elongate shape aligned at an angleddirection compared to a direction of the circumference of the cuff.
 4. Atracheal tube according to claim 2, wherein the bulges are placed in twoor more rows, each row extending in a direction of the circumference ofthe cuff.
 5. A tracheal tube according to claim 4, wherein each row isstaggered in relation to an adjacent row in the direction of thecircumference of the cuff, so that one bulge in a row is placed oppositean area of the membrane without any bulge in the adjacent row in adirection along an axis of the tracheal tube.
 6. A tracheal tubeaccording to claim 3, wherein the bulges in two adjacent rows are placedwith the longitudinal axis of the cuff in different angled directions.7. A tracheal tube according to claim 1, wherein a wall thickness of thecuff in the bulges is less than 30 micrometer.